Is there no end to the variety of Brassica plants we can eat as humans? Cabbage (domestic, Savoy and Napa), broccoli, cauliflower, romanesco, Brussels sprouts, all Brassica.
Brassica of Brassicas, all is Brassica–including the odd-looking (but delicious) kohlrabi.
This odd-looking bulb looks like a cross between a beet and an inflamed green (or purple) agave piña, with beet-like greens fleeing the bulb at odd angles. Both the leaves and the bulb are edible, but it's the bulb that is the money here.
As with any leafy root vegetable, the perkier and better the greens look, the better the bulb below is. And as with any leafy root vegetable, the sooner you get the greens separated from the bulb, the longer both will last.
Treat the greens as you would beet greens, mustard greens or collards; low and slow, simmered with a little vinegar and maybe just a pinch of sugar, or sautéed with garlic and olive oil. Use the root in purée (it makes great mash, especially if you punch it up with some onions or garlic), shred it to make a deeper, earthier coleslaw, braise it like Brussels sprouts (like their miniature cousins, you can't easily overcook kohlrabi), or quarter it and throw it in the slow cooker with a piece of tough beef, some onions and a bottle or two of beer.
Kohlrabi: the chameleon of the Brassica family.